The present invention relates to a color television signal sampling clock phase control system for regenerating a sampling clock of a receiver side so as to synchronize its phase with that of a sampling clock of a transmitter side.
In a conventional color television transmission system comprising transmitter and receiver sides, and a channel for connecting them, when a color television signal is to be sampled at the transmitter side by using a sampling clock which is independent of a channel clock, a method is employed wherein frequency synchronization is performed such that the number of sampling clocks of the transmitter and receiver sides coincide with each other within a predetermined period. Such a method is disclosed in, e.g., Japanese Patent Application No. 52-117613 entitled "Sampling Frequency Synchronizing Apparatus".
In the above conventional method, however, only frequencies of sampling clocks of the transmitter and receiver sides are synchronized with each other, but phase locking is not performed. For this reason, the phase of the color burst of a color television signal regenerated at the receiver side varies from that of an input color television signal of the transmitter side in accordance with the phase shift of sampling clocks. Therefore, when a color television signal is to be edited by using a coded/transmitted signal, phase locking of the color burst must be performed, and hence a phase locking device such as a frame synchronizer is independently required.